How can I generate unique random patterns (similar to the ones in Nutella jars)?
Some excerpts from     Nutella 'Hired' an Algorithm to Design New Jars. And It Was a Sell-Out Success:

The "algorithm" is called HP Mosaic and is included free in HP SmartStream Designer for HP printers.

More about how the algorithm works here: https://www.linkedin.com/pulse/hp-mosaic-20-steven-chow

HP Mosaic takes the vector PDF file as input (also known as a Seed file), and generates a large number of variations on the file by transforming it — scaling, transposition, and rotation — randomly.